This invention relates generally to locomotives and more specifically to an electronic load regulator for use in locomotives. In some embodiments, the invention comprises an electronic load regulation system that may be used in place of prior art mechanical load regulation systems.
Many existing locomotives use prime mover, such as a diesel engine, to turn an electric generator. The electricity produced is supplied to electric traction motors that are used to turn the wheels and propel the locomotive. A first significant factor that impacts the output of the electric generator is the rotating speed of the engine. A higher rotational engine speed causes the generator to output a greater amount of horsepower. A second significant factor is the amount of excitation current in the field windings of the generator. A higher current causes the generator to output a greater amount of horsepower.
The rotating speed of the engine is generally controlled directly by an engineer via the throttle control. A load regulator system then prevents the engine from being overloaded or underloaded by regulating the excitation current in the field windings of the generator at all throttle positions.
FIG. 1 shows a prior art mechanical load regulator system 5 having a large rheostat 6 driven by a hydraulically operated vane motor 10. The input side 7 of the rheostat 6 is connected to the voltage/current source. The output side 8 of the rheostat 6 is connected to the field windings of the electric generator.
Inlets/outlets 11 of the vane motor 10 receive hydraulic fluid from the engine governor. The engine governor is a complex mechanism designed to regulate engine speed. One of its functions is to control the flow of engine oil to the vane motor 10. The output of the vane motor 10 is connected directly to the rheostat 6. Oil flow through the vane motor 10 in one direction will adjust the rheostat 6 to increase the electrical excitation current present in the generator field windings, while oil flow in the opposite direction will adjust the rheostat 6 to decrease the excitation current present in the generator field windings. Thus, hydraulic output from the engine governor controls the rheostat 6, which in turn controls the excitation current present in the generator field windings.
Some locomotives also include a switcher service circuit 4 capable of bypassing the rheostat 6. Under normal road service operation, the rheostat 10 may provide a smooth ramp up of excitation current, which in turn provides smooth acceleration. Under certain conditions, such as when switching railcars that are attached to the locomotive, a more immediate jolt may be desirable. Thus, a switch 3 may be operated to bypass the rheostat 6 and instead use the switcher service circuit 4, which generally provides a more immediate, higher predetermined amount of excitation current.
Maintenance of a prior art mechanical load regulator system 5 is increasingly difficult and expensive. Opens, shorts and dirt build-up in the rheostat 6 can cause erratic behavior of the locomotive's traction control. Vane motors 10 require maintenance and hydraulic leaks also cause erratic behavior.
There remains a need for a load regulator system that avoids drawbacks associated with prior art mechanical load regulator systems. There remains a need for a load regulator system that can be used in place of prior art mechanical load regulator systems.
All U.S. patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.